The present invention relates to offshore structures and particularly structures for conducting drilling and producing operations in the Arctic regions. More particularly, the structure is particularly adapted for conducting operations in the shallow waters of the Beaufort Sea. As is well known, the Beaufort Sea at particular times of the year contains large movements of relatively thick sea ice and offshore drilling structures must withstand this movement. In the past, it has been suggested that any offshore structures based in the shallow waters of the Beaufort Sea have a conical base section to force the moving ice upward, causing it to break due to the tension forces imposed upon the ice. This will cause the large ice features to break into smaller pieces which then can pass safely around the offshore structure.
While the use of conical-shaped bottom sections obviously solves the problem of breaking the large moving ice sheets into smaller sections, the problem still remains of how to provide an outer skin for the conical section that can withstand the loads imposed by the moving ice sheets. One solution suggested by the prior art is described in U.S. Pat No. 4,215,952 where a resilient material is disposed between the wear surface of the conical base section and the support portion thereof. The use of the resilient section is intended to reduce loads imposed upon the structure by the large ice floes. While this is a possible solution, it requires the use of relatively flexible outer surfaces on the conical base in order that the load can be transmitted to the resilient material positioned between the support structure and the outer surface. The key design problem is to avoid excessive concentration of load on the supporting bulkheads.